Fuse cutout



Sept. 14, 1954 Filed July 20, 1950 G. l.. HILL FUSE CUTOUT 3Sheets-Sheet l ATToRNi-:YJ

G. L. HILL FUSE CUTOUT Sept. 14, 1954 INVENTOR GEORGE L ESL /E H/LL BYATTORNEYS FUSE CUTOUT Filed July 20, 1950 3 Sheets-Sheet 3 INVENTORCEGRGE ESL/E H/LL ATTORNEY Patented Sept. 14, 1954 UNITED STATES PATENTyOFFICE 7 Claims.

This invention relates to open type fuse cutouts such as are used inrelatively high voltage circuits. In such cutouts the fuse member ismounted within an expulsion tube, usually of hard ber, which may or maynot ibe surrounded by an outer reinforcing tube of laminated phenolicmaterial. In such fuses the fuse element itself comprises a relativelyrather short fusible link, mounted adjacent the sealed end of the tube,to which is attached a flexible conductor or fpigtail which is quitelong, protruding from the opposite end of the tube. When a fault ocncurs and t'he link ruptures an arc forms within the tube between theopen ends of the circuit and gas pressure generated by the arc expelsthe conductor and the fused metal from the tube with considerable force,thus forming a long gap which breaks the arcand prevents itsreestablishment.

While fuses of this general type which have heretofore been marketedhave been widely used they do fail upon occasion and such failure isaccompanied by a considerable hazard. The pigtail and fused metal arevery hot immediately after the arcing occurs; if blown completely out ofthe vtube they may fall to the ground and set fire to dry grass orrubbish beneath them. This may be prevented by a catch basket secured tothe lower end of the expulsion tube, such basket being perforated topermit egress of the gases, as is shown in my prior Patent No.2,094,013, issued April 5, 1938.

Beside the re hazard above mentioned cases have been known where,"onrelatively light fault currents, the pigtail part of the fuse element isblown out of the expulsion tube but not completely detached; in suchcases a loose end can swing up and around the supporting insulator andmake contact with the supporting hardware or with the hardware on alower crossarm. Under such circumstances there may be cases where adangling conductor is excited indirectly through circuits which have notbroken, forming a serious hazard to linemen climbing the pole on whichthe cutout is mounted. This also is, of course, prevented by the catchbasket described .in the prior patent above referred to.

Other common hazards exist in other types of cutout. I-Iigh speed movingpictures, taken of such equipment under testI show that the arc gasesemitted under heavy faults are of considerable magnitude and may beexpelled to a distance of 8 or 10 feet from the open end of theexpulsion tube. These gases are hot and ionized and may cause flash-overto metallic grounded 2. structures or an adjacent line of another phase.These motion pictures also show that the hot expelled gases mushroomback over the fuse tube and upon occasion may cause flash-over outsideof the tube after the circuit has been interrupted within the tube.

In. order to reduce the hazards above mentioned this dropout type offuse cutout has been devised. In this cutout the fuse tube is used as aswitch arm, the switch being urged into'an open position by a spring,gravity, or both and held closed by a latch mechanism. The latch, inturn, is held in engagement by tension on the fuse element; when thefuse blows the latch is released and the fuse-switch-arm falls open,forming a second air gap in series with the rst and thus reducing theprobability of the arc reestablishing itself when once broken, andpreventing leakage currents which otherwise might char and destroy theexpulsion tube. The primary purpose of this invention is to pro vide acutout of the dropout type which will retain the advantages inherenttherein while at the same time avoiding the above mentioneddifficulties. Specifically, among Athe objects` of this invention are toprovide means whereby a catch-basket and de-ionizing chamber can tbeused in connection with a cutout ofthe drop-out type, and to provide arelease mechanism which `is simple, rugged, economical and at `the sametime completely reliable in operation and to provide an open type dropdown cutout wherein the expulsion tube drops down in longitudinalalignment with the vertical axis of the supporting in.. sulator and islatched in this position after the fuse blows, during circuitinterruption. and to provide an air gap between the top ferrule of thefuse tube and the top line terminal of the cutout after circuitinterruption.

` tends to open the cutout is restrained, not by the tension on the fuseelement itself, but by a hook or latch which is mounted off-center sothat it tends to disengage under the stress of the spring. The flexibleconductor of the fuse element, when the fuse is set, is passed aroundthis hook and holds it in engagement, thus requiring a very small stressin comparison with the total pressure of the spring. Upon rupture of thefuse, however, this tension of the flexible conductor upon the 'hook isreleased and it immediately disengages. y

V `The above will be more readily understood by reference to the ensuingdetailed description of 3, certain preferred embodiments of thisinvention, taken in connection with the accompanying drawings wherein: f

Fig. 1 is an elevation of the cutout closed position, the upper end ofthe expulsion tube being shown partly in section Fig. 2 is a similarelevation showing a slightly modified form of cutout in the positionassumed when the fuse has blown;

Fig. 3 is a transverse sectional view of a portion of the cutout of Fig.l, the plane of section being indicated by the lines 3-3 in the firstfigure;

Fig. 4 is a fragmentary sectional view of the lower end of the cutout ofFig. 1, the plane of section being indicated by the appropriatelynumbered lines of Fig. 3;

Fig. 5 is a longitudinal sectional view of the lower end of a fuse andlatch mechanism showing a modified mechanical structure; and

A Fig. 6 is a front elevation ofv the structure shown in'Fig. 5, thepla-ne of section of vthe last `narnedffigure being indicated by thelines 1 1. f The two variant forms of the invention shown fin Figs. 1and 2 are so nearly the same that they will be described together, theminor differences being indicated in the course of the explanation.vBoth forms of the device comprise the usual insulator I, usually ofporcelain. This insulator Ais provided with abracket 3, shown only inpart, fwhereby the insulator is secured to a. crossarm y'or otherstructure upon which the cutout is to be mounted.

- vThe upper end of the insulator I carries yan upper contact bracket 5which may be of purely Yconventional type. Secured to this contact-bracket, by a clamp 1, is an upper contact spring 9-. This may be ofPhosphor bronze wire formed 'into a loop,-only one vside of which isshown in the drawings. The spring has considerable strength and isintended to press against the upper ierrule or contact of the fuseitself. -It is indented upwardly, as `shown at 9', to engage a fuseferrule and is provided with a slanted end 9", forming a ramp againstwhich the ferrule bears as the fuse A'ls closed to raisethe spring `andpermit the end of the fuse to latch into the indentation.

"f The 4lower end of the Phosphor vbronze wires of `which `the contactis formed may be brought up varound the clamp and formed into arcinghorns as best indicated at II inFig. 2, the horn being broken away -inFig. 1 to show theconstruotion of Vthefuse itself. VAll of thisstructure is largely Yconventional rand is described here only for the'sake of completeness Aas it is not directly the subject of the presentinvention.

Atthe other end of the insulator I is a lower bracket I3. To this isfastened a hook-shaped trunnion bearing member I5. This comprises a pairof hooks, only the nearer -of which appears `in the drawing,` thesehooks being provided with projecting lips I5 which merge with ovalrecesses I1 f or receiving trunnions I9 on a'U shapedguide Imember A29.Both the bracket 5 and bracket I3 areprovided with terminals, 23 and2-3', to which the line 25 to be protected by the fuse cutout issecured.

- `In the form of the device shown in Fig. 2 the 'trunnion bearingmember |-5 is also provided with a spring latchf24, forengaging the Ushaped guide member 2|i and preventing-'it from `swing- 'ing outward,when the fuse blows, unt-il purposely 'released bya maintenance man forthe purpose of replacing the fuse. The U shaped guide vmember 26 itselfmay be formed of sheet metal. It comprises-a `substantially ver-ticalplate 29, `the sides of which are bent back to form flanges 2 |I to addstiffness and support to the trunnion I9. Substantially parallelhorizontal arms 21 and 29 project forwardly from the plate 26, the wholeguide member 26 being generally U-shaped with the base of the Uvertical. Both of the arms of the U are apertured so as to receiveslideably the expulsion tube 3| of the fuse itself. The latter issurrounded by a compression spring 33 which bears against the upper arm21 and a flange 35 `which surrounds and is secured to the expulsion tubeby the set screw 34. When the fuse is loaded and in the unblowncondition the spring 33 is compressed as shown in Fig. 1. When the fuseis blown the spring forces the entire fuse assembly downward until theflange 35 strikes against the lower bracket 29 as shown in Fig. 2. Thisaction is normally prevented by a hook or latch 31 which swings from apivot 39 on the arm 29. The latch engages a recess in a basket 4|screwed to the `lower end of the expulsion tube 3|. The basket will bedescribed more in detail hereinafter.

As will be seen the hook or latch 31 is generally L-shaped, and thepivot 39 is laterally displaced from the foot or latch portion of the L.There is, accordingly, a lateral lever arm which tends to rotate thehook around its pivot and disengage it. This is prevented by theflexible copper conductor 43 of the fuse element itself which passesaround and over the hook and is secured to a suitable binding post orconnector 45 on the'lower arm 29 of the U shaped guide member V26.

The expulsion tube 3| is preferably formed of Bakelite tubing or otherwater resistant and mechanically strong material and is provided with aliner `41 which may be of horn fiber tubing. This, of course, is aconventional construction. Screwed to its upper end is a ferr-ule 49,which is of highconductivity metal such as brass or bronze and isprovided with a reduced end or thimble r49. This thimble is externallythreaded to receive a ferrule cap 5|. The ferrule and thimble are tu"-bular, and the fuse assembly is provided witha flange 53 which rests onthe end -of the thimble and is held in place by the ferr-ule cap untilsuch time as the cutout is loaded, when the stress on the conductor orpigtail 43, of course, holds itin place. The ferrule cap 5| forms theactual upper contact of the fuse against which the contact spring 9presses and also serves as a closure or Aseal `for the upper end of 'theexpulsion tube. A pullring 52, for manipulating the fuse, is lsecured tothe upper end of the tube.

The lower ferrule 55 and catch basket Il is fshown in detail in Fig. 4and is an improvement to that described in my prior Patent No. 2,094,013uabove mentioned. It comprises a -threaded metal ferrule 55 screwed orotherwise secured to the expulsion tube 3|. Threaded onto the 'ferruleis Ythe catch or deionizing basket 4| proper, this being of brass,bronze, or the like, and being formed with an interior chamber 51.Apertures 59 are formed at the bottom of the catch basket `and there arepreferably provided, betweenthe walls of chamber 51 andthe sides of thebasket itself, means for condensing the hot Ygases resulting from theVare formed upon blowing lof lthe fuse. Such means may comprisecoiled-corrugated copper strip 6I-. Strips of copper netting maylikewise be usedif desired.

An additional aperture 63, as shown Sin Fig. 4 is formed on one side ofthe 'catch basket. upper edge of this latter aperture forms -a lip whichis engaged by- Athe hook 31; the aperture isl of sufiicient size toadmit the `endl-of the pigtail finder the hook when the latter isengaged, thence passing around it and up to the binding post 45.

From what has been described the operation of the device under a faultshould be apparent. When the fuse blows the gases generated by the areexpel the pigtail from the tube into the chamber l of the basket, whereit is held and kept from swinging and causing damage which has beendescribed above. Gases, escaping from the basket through the vent holes59, are cooled materially by passing through the condensing strips 8|,thus reducing the re and ilashover hazard. As this occurs theconstraining action of the pigtail upon the hook 3l is released and itimmediately swings out of the way, as indicated in Fig. 2, and the fuseis forced down by the powerful spring 33 out of contact with the uppercontact of latch spring 9. If the form of the device shown in Fig. 1 isused the off-center weight of the entire mechanism swings it around thetrunnions I9 and opens the auxiliary gap more widely, not only tendingto prevent reestablishment of the arc but also visibly signalling theblowing of the fuse. Normally the upper contact is made to the live orsupply side of the line, thus minimizing the danger encountered inreplacing the ruse and closing the cutout. This is usually done by meansof a fuse stick, consisting of a hook mounted upon a pole, which engagesthe pull-ring The fuse tube and the U-shaped member 28 can be liftedout-of the trunnion bearing member I5 with the fuse stick, the fusereplaced, the device reset and the whole assembly can then be'reengagedin the trunnion bearing member and the cutout closed.

In the case of the form shown in Fig. 2 the only difference in thisoperation is that instead of the fuse swinging outwardly upon blowing itis held in place by they latch 24 until released by a sharp outward tugon the pull-ring 52.

From the arrangement of the mechanism of the cutout itself it should beevident that a large number of modifications are possible withoutdeparting from the spirit of this invention. One such modication isshown in Figs. 5 and 6. The modification referred to concernsparticularly the U-shaped guide member 99, ferrule ||9 and deionizmgchamber 4|', ferrule and de-ionizing chamber; the insulator, uppercontacts, and trunnion bearing member l5 employed therewith may beidentical to that already described or may themselves be modiiied. TheU-shaped guide member 99 itself, however, is formed of sheet materialwhich is bent into the shape shown. Like the one previously described itis generally U- shaped, comprising a pair of substantially parallelhorizontal arms 95 and |0| apertured to receive the fuse, 'the arms,however, projecting inwardly in this case. Of these arms the lower,designated by the reference character 95, is provided with anges 91 oneach edge. These flanges are bent up from the sides of the arm and arelobed at the end to carry trunnion pin I9.

Distantly from the trunnion I9 the lower horizontal arm 95 is bentupward at right angles to form a backplate 99, above which it is bentinwardly again to form the arm |0|. being the upper of the two parallelarms of the U-shaped guide member 99.

The backplate carries a conventional binding post |03 for securing theends of the pigtail 43. Below the binding post there is formed slot |05shaped like the letter `H laid on its'side. Two short tabs |01 extendinghorizontally toward each other and separated by the cross bar of the H,

.form 'the pivots on which the hook or latch Y 31. is swung. Ihe hook isdouble, being punchedor otherwise formed from two identical pieces ofsheet metal, separated by a smallstrut |09, the ends of which arerivetted to secure the two sides of the hook in place. To assemble thisdevice the two sides are pressedtogether and inserted between the tabs|01, and then allowed to spring back into place.

In this form of the device the fuse itself is also slightly modified.The expulsion tube 3|' is provided with a tubular metallic extension Iwhich projects upwardly through the aperture in the lower arm and isthreaded to the lower end of the expulsion tube. A ilange 35', betweenwhich and the upper arm I0| the spring 33' is compressed, is held inplace on the upper end of the extension |0| by a split -spring-ring ||3fitting in a groove in the extension in well known manner. Below thelower arm 95 the extension is provided with asection l5 of somewhatlarger diameter, on the end of which is formed a threaded coupling Ill.The catch basket 4I is screwed to` this coupling. This basket diiTers inshape, but not in function, from the catch basket 4| previouslydescribed.

An orice I I9 is formed in the portion |5 above the coupling, and a lip|2| extends outwardly above this orice for engagement by the hook 3l'.In setting the fuse the pigtail 43 is brought out through this orice andover the rivetted strut |09 tothe binding post |03, where it is secured.

It should be quite apparent that the advantages of the -constructionsherein described are not limited to the specic type of release'shown butthat the combination of a hook latch which carries the major portion ofthe stress applied by a spring which tends to open the cutout but isheld in engagement by the fuse link assembly can be used in many otherforms. I therefore do not desire to be limited to the exact structuresherein described but rather to obtain the full protection warranted bythe scope of the following claims.

I claim: 1.' In a fuse cutout of the dropout type employing a fusecomprising an expulsion tube enclosing a fuse link provided with aflexible conductor extending therefrom; a guide member for holding saidfuse comprising upper and lower substantially parallel arms apertured toreceive slideably said expulsion tube, a compression spring between saidarm and proportioned to surround said expulsion tube, bearing againstsaid upper arm and said tube to force the latter downward, and latchingmeans for retaining said tube in said guide member and said spring incompression and means for securing the flexible conductor of said fuselink to said guide member around said latching means to hold the same inengagement until said fuse ruptures,

2. In a dropout fuse cutout of the type wherein tension on a fuse linkis employed to restrain a spring tending to open said cutout; afuseassembly including an expulsion tube, a fuse member having a fusiblelink and a flexible conductor secured thereto within said tube and acontact ferrule to which one end of said fuse member is secured, one endof said conductor projecting from said expulsion tube at the endopposite said ferrule, a resilient contact for said ferrule, a pair ofsubstantially parallel arms apertured for mounting said assemblyslidably with respect to saidspring contact, a spring mounted betweensaid arms and bearing against one of said arms' @maar and said assemblyto move said fuse and ferrule out of engagement with said contact, andlatchlng means for retaining said ferrule in engagement against theaction'of said `spring while said fuse member is unruptured.

3. A drop-out type expulsion fuse cutout comprising Ia supportinginsulator, -upper and lower contacts on said insulator and a bearing onsaid lower contact, a fuse assembly comprising an insulating expulsiontube, an upper contact ferrule, means for securing a fuse element withinVsaid tube to said ferrule and a `lower Ierrule apertured laterally topermita exible-conductor attached to said fuse element to projectoutwardly therethrough; a metallic guide member on they tube pivotallymountable in said bearing and including a pair of spaced guide membershaving holes therein for slidably engaging said fuse `assembly andretaining it in alinement :between said contacts when said cutout is inclosed position, a latch on said guide member engageable with said fuseassembly to retain it in longitudinal position to engage said uppercontact, and means on said guide member for securing the uprojecting endof said flexible conductor over said latch to retain it in engagement solong as said fuse element is intact.

4. A drop-out type expulsion fuse cutout comprising a supportinginsulator, upper and lower contacts mounted on said insulator; a fuseassembly comprising an insulating expulsion tube, an upper contactferrule mounted on said tube, means within said ferrule for securingthereto a fuse element comprising a `fusible llink and an extendedflexible conductor for connection with said lower contact, 'a lowerfer-rule with a lateral aperture for passage of the conductor and anapertured bottom; a catch-basket attached to the apertured bottomierrule for retaining portions of said fuse element expelled from saidtube upon rupture of said fusible link while permitting downward escapeof gases resulting from such rupture, a trunnion hinged to said lowercontact and engaging said fuse assembly above said catchbasket and outof the path of gasesdischarged through .the apertures therein, latchingmeans for holding said fuse assembly against rotation about its hingeand maintaining said upper :ferrule against said upper contact, andmeans for securing'the end of saidilexible'conductor to hold saidlatching means in engagement las long as said fuse element is intact.

5. In combination, a dropout `fuse cutout corn- I prising upper andlower yterminal members mounted on an insulator, a bearing for atrunnion on the lower terminal Vmemberfan expulsion fuse tube betweenthe terminal members, a U- shaped metallic member on the-lower end ofthe tube, said tube passing through apertures in the extended parts ofthe VU -shaped metallic member, a trunnion pin on the U-shaped metallicmember for insertion in the trunnion bearing, a fuse link `within theYexpulsion tube, a compression spring for tensioning the fuse link, alatch for holding the tube in position and sustaining a large percentageof the force exerted by said spring, a terminal for the flexibleconductor of said link land a catching and cooling chamber `on the openend of the expulsion tube for catching the expelled parts and coolingthe gases during circuit interruption.

6. An expulsion cutout comprising upper and lower terminal membersmounted on an insulator, an expulsion fusev tube between the terminalmembers, a U-shaped metallic member on the lower end of the tube, saidtube passing through the `extended parts of the `U-shapefl metallicmember, a collar on the tube within the U-shaped metallic member, acompression spring between the collar and the upper part of the U-shapedmetallic member, a latch member mounted on `the lower terminal memberengaging :the U- circuit interruption.

'7. In combination an open type drop-out fuse cutout comprising asupporting insulator, an upper terminal and a lower terminal mountedthereon, a trunnion bearing on the lower terminal anexpulsion fuse tubefor insertion in the terminals, a metallic `member mounted on the lowerend of the expulsion tube, a trunnion on the Ametallic member forinsertion in the trunnion bearing and Ia latch mounted on the metallicmember for restraining the expulsion tube in the closed position, a fuselink in the expulsion tube, said fuse link having its exible conductorhold the latch member in thenormal closed position, and a catching a-ndcie-ionizing chamber on the open end ofthe expulsion tube, said chamberconsisting of an inner chamber for the reception of the expelled `partsof the fuse link and `an outer'chamber containing a cooling means andapertured for the escape of gases.

4References Cited in theflle of this patent UNITED STATES PATENTS NumberName Date 2,094,013 Hill Sept. 28, 1937 2,151,159 Schultz Mar. 21, 19392,203,928 Schultz June 11, 1940 2,231,510 Schultz Feb. 11, 19412,291,646 Ramsey Aug. 4, 1942 2,334,134 Steinmayer et al. Nov. 9, 19432,365,113 `Schultz Dec. 12, 1944 2,394,599 Boothe Feb. 12, 19462,458,742 Schultz Jan. 11, 1949 2,466,486 Schultz Apr. 5,1949 2,493,601Smith, Jr Jan. `3, 1950

